Fun with ranges!

ruby-talk
1

So I was messing around today trying to find out whether there was a
viable way to cram unbounded lists into the Range implementation when
I stumbled on this...

irb(main):001:0> inf = 1.0/0.0
=> Infinity

irb(main):002:0> 1..inf
=> 1..Infinity

Hoorah! But not just that.

irb(main):003:0> 'a'..inf
=> "a"..Infinity

Hold on a second, I said to myself, that doesn't make any sense... inf
is a Float and "a" is a string! That's when I discovered ruby's
dastardly secret:

irb(main):004:0> 'a' <=> 3
=> false
irb(main):005:0> 3 <=> 'a'
=> nil

And hence:

irb(main):006:0> 'a'..3
=> "a"..3
irb(main):007:0> 3..'a'
ArgumentError: bad value for range
        from (irb):7

Zounds,

Sam

2

Hi --

···

On Sat, 26 Nov 2005, Sam Gentle wrote:

So I was messing around today trying to find out whether there was a
viable way to cram unbounded lists into the Range implementation when
I stumbled on this...

irb(main):001:0> inf = 1.0/0.0
=> Infinity

irb(main):002:0> 1..inf
=> 1..Infinity

Hoorah! But not just that.

irb(main):003:0> 'a'..inf
=> "a"..Infinity

Hold on a second, I said to myself, that doesn't make any sense... inf
is a Float and "a" is a string! That's when I discovered ruby's
dastardly secret:

irb(main):004:0> 'a' <=> 3
=> false
irb(main):005:0> 3 <=> 'a'
=> nil

And hence:

irb(main):006:0> 'a'..3
=> "a"..3
irb(main):007:0> 3..'a'
ArgumentError: bad value for range
       from (irb):7

What version of Ruby are you using?

$ ruby -ve '"a"..3'
ruby 1.8.3 (2005-09-21) [powerpc-darwin8.3.0]
-e:1: warning: useless use of .. in void context
-e:1: bad value for range (ArgumentError)

David

--
David A. Black
dblack@wobblini.net

3

C:\>ruby -ve '"a"..3'
ruby 1.8.2 (2005-02-01) [i386-mswin32]
-e:1: warning: useless use of .. in void context

Strange...

weill samg$ ruby -ve '"a"..3'
ruby 1.8.0 (2003-08-04) [i686-linux]
-e:1: warning: useless use of .. in void context
-e:1: bad value for range (ArgumentError)

Double-strange... I wonder if it's a windows thing or a version thing
(and if so why it only pops up somewhere between 1.8.0 and 1.8.3).

Sam

···

On 11/26/05, David A. Black <dblack@wobblini.net> wrote:

What version of Ruby are you using?

$ ruby -ve '"a"..3'
ruby 1.8.3 (2005-09-21) [powerpc-darwin8.3.0]
-e:1: warning: useless use of .. in void context
-e:1: bad value for range (ArgumentError)

4

Hi --

···

On Sat, 26 Nov 2005, Sam Gentle wrote:

On 11/26/05, David A. Black <dblack@wobblini.net> wrote:

What version of Ruby are you using?

$ ruby -ve '"a"..3'
ruby 1.8.3 (2005-09-21) [powerpc-darwin8.3.0]
-e:1: warning: useless use of .. in void context
-e:1: bad value for range (ArgumentError)

C:\>ruby -ve '"a"..3'
ruby 1.8.2 (2005-02-01) [i386-mswin32]
-e:1: warning: useless use of .. in void context

Strange...

weill samg$ ruby -ve '"a"..3'
ruby 1.8.0 (2003-08-04) [i686-linux]
-e:1: warning: useless use of .. in void context
-e:1: bad value for range (ArgumentError)

Double-strange... I wonder if it's a windows thing or a version thing
(and if so why it only pops up somewhere between 1.8.0 and 1.8.3).

Interesting -- it seems to be a 1.8.2 thing.

David

--
David A. Black
dblack@wobblini.net